The present invention relates to operational amplifiers and, more particularly, to an integrated operational amplifier having an all NPN output stage including circuitry for increasing the magnitude of the current sourced to the output of the amplifier.
An all NPN output stage for operational amplifiers (op-amps) is well known in the art. In todays marketplace there are many applications for such op-amps which have low power consumption in order, for example, to be utilized in battery operated systems. The problem with most if not all prior art low power op-amps is that they can not drive small resistive loads, i.e., loads of 600 ohms or less because of limited ability to source sufficient load current while maintaining minimum drain current in the quiescent operating mode.
Thus, a need exists for a low power operational amplifier having means for boosting the output source current as a function of the load while maintaining low power drain.